video_stream_encoder_interface.h

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/*

 *  Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.

 *  Use of this source code is governed by a BSD-style license

 *  that can be found in the LICENSE file in the root of the source

 *  tree. An additional intellectual property rights grant can be found

 *  in the file PATENTS.  All contributing project authors may

 *  be found in the AUTHORS file in the root of the source tree.

*/

#ifndef VIDEO_VIDEO_STREAM_ENCODER_INTERFACE_H_

#define VIDEO_VIDEO_STREAM_ENCODER_INTERFACE_H_

#include <vector>

#include "api/adaptation/resource.h"

#include "api/fec_controller_override.h"

#include "api/rtc_error.h"

#include "api/rtp_parameters.h"  // For DegradationPreference.

#include "api/rtp_sender_interface.h"

#include "api/scoped_refptr.h"

#include "api/units/data_rate.h"

#include "api/video/video_bitrate_allocator.h"

#include "api/video/video_layers_allocation.h"

#include "api/video/video_sink_interface.h"

#include "api/video/video_source_interface.h"

#include "api/video_codecs/video_encoder.h"

#include "video/config/video_encoder_config.h"

namespace webrtc {

// This interface represents a class responsible for creating and driving the

// encoder(s) for a single video stream. It is also responsible for adaptation

// decisions related to video quality, requesting reduced frame rate or

// resolution from the VideoSource when needed.

// TODO(bugs.webrtc.org/8830): This interface is under development. Changes

// under consideration include:

//

// 1. Taking out responsibility for adaptation decisions, instead only reporting

//    per-frame measurements to the decision maker.

//

// 2. Moving responsibility for simulcast and for software fallback into this

//    class.

class VideoStreamEncoderInterface {

 public:

  // Interface for receiving encoded video frames and notifications about

  // configuration changes.

  class EncoderSink : public EncodedImageCallback {

   public:

    virtual void OnEncoderConfigurationChanged(

        std::vector<VideoStream> streams,

        bool is_svc,

        VideoEncoderConfig::ContentType content_type,

        int min_transmit_bitrate_bps) = 0;

    virtual void OnBitrateAllocationUpdated(

        const VideoBitrateAllocation& allocation) = 0;

    virtual void OnVideoLayersAllocationUpdated(

        VideoLayersAllocation allocation) = 0;

};

  virtual ~VideoStreamEncoderInterface() = default;

  // If the resource is overusing, the VideoStreamEncoder will try to reduce

  // resolution or frame rate until no resource is overusing.

  // TODO(https://crbug.com/webrtc/11565): When the ResourceAdaptationProcessor

  // is moved to Call this method could be deleted altogether in favor of

  // Call-level APIs only.

  virtual void AddAdaptationResource(rtc::scoped_refptr<Resource> resource) = 0;

  virtual std::vector<rtc::scoped_refptr<Resource>>

  GetAdaptationResources() = 0;

  // Sets the source that will provide video frames to the VideoStreamEncoder's

  // OnFrame method. `degradation_preference` control whether or not resolution

  // or frame rate may be reduced. The VideoStreamEncoder registers itself with

  // `source`, and signals adaptation decisions to the source in the form of

  // VideoSinkWants.

  // TODO(bugs.webrtc.org/14246): When adaptation logic is extracted from this

  // class, it no longer needs to know the source.

  virtual void SetSource(

      rtc::VideoSourceInterface<VideoFrame>* source,

      const DegradationPreference& degradation_preference) = 0;

  // Sets the `sink` that gets the encoded frames. `rotation_applied` means

  // that the source must support rotation. Only set `rotation_applied` if the

  // remote side does not support the rotation extension.

  virtual void SetSink(EncoderSink* sink, bool rotation_applied) = 0;

  // Sets an initial bitrate, later overriden by OnBitrateUpdated. Mainly

  // affects the resolution of the initial key frame: If incoming frames are

  // larger than reasonable for the start bitrate, and scaling is enabled,

  // VideoStreamEncoder asks the source to scale down and drops a few initial

  // frames.

  // TODO(nisse): This is a poor interface, and mixes bandwidth estimation and

  // codec configuration in an undesired way. For the actual send bandwidth, we

  // should always be somewhat conservative, but we may nevertheless want to let

  // the application configure a more optimistic quality for the initial

  // resolution. Should be replaced by a construction time setting.

  virtual void SetStartBitrate(int start_bitrate_bps) = 0;

  // Request a key frame. Used for signalling from the remote receiver with

  // no arguments and for RTCRtpSender.generateKeyFrame with a list of

  // rids/layers.

  virtual void SendKeyFrame(const std::vector<VideoFrameType>& layers = {}) = 0;

  // Inform the encoder that a loss has occurred.

  virtual void OnLossNotification(

      const VideoEncoder::LossNotification& loss_notification) = 0;

  // Set the currently estimated network properties. A `target_bitrate`

  // of zero pauses the encoder.

  // `stable_target_bitrate` is a filtered version of `target_bitrate`. It  is

  // always less or equal to it. It can be used to avoid rapid changes of

  // expensive encoding settings, such as resolution.

  // `link_allocation` is the bandwidth available for this video stream on the

  // network link. It is always at least `target_bitrate` but may be higher

  // if we are not network constrained.

  virtual void OnBitrateUpdated(DataRate target_bitrate,

                                DataRate stable_target_bitrate,

                                DataRate link_allocation,

                                uint8_t fraction_lost,

                                int64_t round_trip_time_ms,

                                double cwnd_reduce_ratio) = 0;

  // Set a FecControllerOverride, through which the encoder may override

  // decisions made by FecController.

  virtual void SetFecControllerOverride(

      FecControllerOverride* fec_controller_override) = 0;

  // Creates and configures an encoder with the given `config`. The

  // `max_data_payload_length` is used to support single NAL unit

  // packetization for H.264.

  virtual void ConfigureEncoder(VideoEncoderConfig config,

                                size_t max_data_payload_length) = 0;

  virtual void ConfigureEncoder(VideoEncoderConfig config,

                                size_t max_data_payload_length,

                                SetParametersCallback callback) = 0;

  // Permanently stop encoding. After this method has returned, it is

  // guaranteed that no encoded frames will be delivered to the sink.

  virtual void Stop() = 0;

};

}  // namespace webrtc

#endif  // VIDEO_VIDEO_STREAM_ENCODER_INTERFACE_H_